Brillant Green Bile Broth

Brilliant green bile (BGB) broth is a modification of MacConkey’s liquid medium for the isolation of Enterobacteriaceae and has been formulated to attain maximum recovery of bacteria of the coli-aerogenes group, while inhibiting most gram-positive organisms that might hinder the development of the bacteria sought. It contains brilliant green and bile as the inhibitory agents for gram-positive organisms and lactose as the carbon source that is dissimilated rapidly by the coli-aerogenes group, mostly by a heterofermentative pathway, leading to gas formation. It is markedly superior to MacConkey broth for the confirmation of Escherichia coli at 44° C. BGB broth is composed of peptone, lactose, ox bile, brilliant green, and distilled or deionized water. This chapter describes the preparation of BGB. Ingredients are dissolved in water, distribute in the required volumes in flasks or tubes, and heated at 100° C for 30 minutes. Although lactose media are markedly less sensitive to heat damage than those containing glucose, the performance of the medium with respect to both selectivity and productivity is much more consistent when it is decontaminated by standardized pasteurization as recommended.